The effects of the 2023 bird flu outbreak on the population biology of Common Guillemots on Skomer Island

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作   者：

Tim R. Birkhead;  Ben J. Hatchwell; 

作者机构：

University of Sheffield;  Department of Biological Sciences;  Sheffield S10 2TN; 

期刊名称：

British Birds

i s s n：

0007-0335

年卷期：

2025 年 118 卷 1 期

页   码：

8-19

页   码：

摘   要：

The outbreak of Highly Pathogenic Avian Influenza (HPAI, ‘bird flu’) first detected in the UK in 2021 has resulted in the deaths of millions of birds, both domesticated and wild, and is a major conservation threat to seabirds. During the summer of 2023, HPAI killed many Common Guillemots Uria aalge in Britain. Amongst the birds killed on Skomer Island, Pembrokeshire, were a number of ringed individuals from a long-term population study there. This paper makes a preliminary assessment of the impactof HPAI-driven mortality on the Skomer Guillemot population.This assessment was complicated by the fact that, for the first time in the 50-year history of the study, there was clear evidence that in 2023, prior to the HPAI outbreak later that summer, Guillemots were short of food, evidenced by a late breeding season, unusually low off-duty partner attendance during chick-rearing, and underweight chicks. The number of recoveries of Skomer-ringed Guillemots during July and August 2023 - assumed to be dueto HPAI - was greater than in any previous year of the study. To assess the impact of events in 2023, we monitored the breeding population in 2024 and found that sightings of ringed Guillemots (indicative of adult survival) were 20-30% lower than in previous years. There was also clear evidence of ‘compensatory recruitment’ in 2024, with younger birds moving into the colony to occupy sites left vacant by HPAI deaths. This, together with a reduction in breeding density, resulted in relatively low breeding success (0.68 chicks/pair) in 2024 compared with previous recent years (0.80 chicks/pair). The timing of egg-laying and off-duty partner attendance were both apparently normal in 2024, suggesting that food supplies were not compromised. Overall, we estimate that the 2023 bird flu outbreak resulted in the loss of 20-30% of the Guillemot population on Skomer, a figure presumably mirrored across other colonies in South Wales.The full impact of the HPAI outbreak on the Guillemot population, however, will take several years to elucidate.